1. Field of the Invention
The present invention relates to a semiconductor device, in particular, to a semiconductor device having a bonding pad.
2. Description of the Related Art
A semiconductor device must pass various reliability stress tests in order to guarantee the long-term reliability. For example, a test in which a high temperature, a high humidity, and a bias are combined is widely used, such as a high-temperature high-humidity bias test performed under a condition of a temperature of 85° C. and a humidity of 85% and a pressure cooker bias test performed under a condition of a temperature of 125° C., a humidity of 85%, and a pressure of 2 atm. These tests are defined, for example, by the JEDEC standard in view of an actual environment of the market, which are intended to prevent an occurrence of a problem at the market. These tests form a basic guideline for guaranteeing the long-term reliability at the market, which is also needed in order to prevent an occurrence of market defect.
During these high-temperature and high-humidity tests, there may be a case where some moisture having passed through a package resin penetrates into a chip from an opening portion of a pad or the like, and makes an electrochemical reaction to oxidize an interconnecting line, so that a reliability problem occurs due to a volume expansion or an interfacial peeling. In order to prevent such a problem, an invention has been disclosed, which prevents the penetration of the moisture by removing a titanium nitride film formed on a pad in a ring shape or a slit shape in a peripheral portion of a bonding pad (see, for example, Japanese Published Patent Application 2010-251537).
Problems to be solved by the current disclosure are as follows.
As described above, during the high-temperature and high-humidity test, there may be a case where the moisture having passed through a package resin penetrates into a chip from an opening portion of a pad or the like, and makes an electrochemical reaction to oxidize an interconnecting line, so that a reliability problem occurs due to a volume expansion or an interfacial peeling. As a measure against the problem, it can be considered to prevent the penetration of the moisture into the chip by modifying the package resin or by modifying a pad structure. However, in some cases, such a measure is far from being perfect. Although the moisture does not pass through the nitride film and aluminum interconnecting line, the moisture penetrates into the chip through the oxide film, an interface between the oxide film and the aluminum interconnection film, and the like. Some way of blocking these penetration paths is required as the measure against this phenomenon.